Hi Michael, It's pretty easy with reshape:
library(reshape2) ucbm <- melt(UCBAdmissions) acast(ucbm, Admit + Gender ~ Dept) acast(ucbm, Admit ~ Dept + Gender) acast(ucbm, Admit + Dept + Gender ~ .) # You can also do aggregations acast(ucbm, Admit ~ Dept, fun = sum) Hadley On Thu, Jan 9, 2014 at 9:14 AM, Michael Friendly <frien...@yorku.ca> wrote: > Given a 3+ way table, I'd like a simple, elegant way to flatten the table to > a two-way > table, with some variables joined interactively to form the rows and others > forming > the columns. For example, starting with > >> str(UCBAdmissions) > table [1:2, 1:2, 1:6] 512 313 89 19 353 207 17 8 120 205 ... > - attr(*, "dimnames")=List of 3 > ..$ Admit : chr [1:2] "Admitted" "Rejected" > ..$ Gender: chr [1:2] "Male" "Female" > ..$ Dept : chr [1:6] "A" "B" "C" "D" ... >> > > What I want is something similar to the result of ftable: > >> ftable(UCBAdmissions) > Dept A B C D E F > Admit Gender > Admitted Male 512 353 120 138 53 22 > Female 89 17 202 131 94 24 > Rejected Male 313 207 205 279 138 351 > Female 19 8 391 244 299 317 > > One way to do this is to convert to a data.frame, paste the factors together > and then convert back to a table: > > UCB.df <- as.data.frame(UCBAdmissions) > UCB.df$`Admit:Gender` <- paste(UCB.df$Admit, UCB.df$Gender, sep=':') > UCB.tab2 <- xtabs(Freq ~ `Admit:Gender` + Dept, data=UCB.df) > UCB.tab2 > >> UCB.tab2 > Dept > Admit:Gender A B C D E F > Admitted:Female 89 17 202 131 94 24 > Admitted:Male 512 353 120 138 53 22 > Rejected:Female 19 8 391 244 299 317 > Rejected:Male 313 207 205 279 138 351 >> > > But maybe there is a simpler, more elegant and general way to do this. > > -- > Michael Friendly Email: friendly AT yorku DOT ca > Professor, Psychology Dept. & Chair, Quantitative Methods > York University Voice: 416 736-2100 x66249 Fax: 416 736-5814 > 4700 Keele Street Web:http://www.datavis.ca > Toronto, ONT M3J 1P3 CANADA > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- http://had.co.nz/ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
